Eco-friendly deacetylated chitosan base siRNA biological-nanopesticide loading cyromazine for efficiently controlling Spodoptera frugiperda

Chitosan-based insecticide formulations for insect pest control management: A review of current trends and challenges

Future agricultural practices necessitate green alternatives to replace hazardous insecticides while distinguishing between pests and beneficial insects. Chitosan, as a biological macromolecule derived from chitin, is biodegradable and exhibits low toxicity to non-target organisms, making it a sustainable alternative to synthetic pesticides. This review identifies chitosan-derivatives for insecticidal activity and highlights its efficacy including genotoxicity, defense mechanism, and disruption of insect's exoskeleton at different concentrations against several insect pests. Similarly, synergistic effects of chitosan in combination with natural extracts, essential oils, and plant-derived compounds, enhances insecticidal action against various pests was evaluated. The chitosan-based insecticide formulations (CHIF) in the form of emulsions, microcapsules, and nanoparticles showed efficient insecticide action on the targeted pests with less environmental impact. The current challenges associated with the field-trial application were also recognized, by optimizing potent CHIF-formulation parameters, scaling-up process, and regulatory hurdles addressed alongside potential solutions. These findings will provide insight into achieving the EU mission of reducing chemical pesticides by 50 %.

Nanomaterial-Encapsulated dsRNA-Targeting Chitin Pathway─A Potential Efficient and Eco-Friendly Strategy against Cotton Aphid, Aphis gossypii (Hemiptera: Aphididae)

The r-strategy pests are very challenging to effectively control because of their rapid population growth and strong resurgence potential and are more prone to developing pesticide resistance. As a typical r-strategy pest, the cosmopolitan cotton aphid, Aphis gossypii Glover, seriously impacts the growth and production of cucurbits and cotton. The present study developed a SPc/double-stranded RNA (dsRNA)/botanical strategy to enhance the control efficacy of A. gossypii. The results demonstrated that the expression of two chitin pathway genes AgCHS2 and AgHK2 notably changed in A. gossypii after treated by three botanical pesticides, 1% azadirachtin, 1% matrine, and 5% eucalyptol. SPc nanocarrier could significantly enhance the environmental stability, cuticle penetration, and interference efficiency of dsRNA products. The SPc/dsRNA/botanical complex could obviously increase the mortality of A. gossypii in both laboratory and greenhouse conditions. This study provides an eco-friendly control technique for enhanced mortality of A. gossypii and lower application of chemical pesticides. Given the conservative feature of chitin pathway genes, this strategy would also shed light on the promotion of management strategies against other r-strategy pests using dsRNA/botanical complex nanopesticides.

Exploring chitin: novel pathways and structures as promising targets for biopesticides

Chitin, the most prevalent polymer in nature, a significant structural polysaccharide that comes in second only to cellulose. Chitin is a crucial component of fungal cell walls and also present in many other creatures, such as viruses, plants, animals, insect exoskeletons, and crustacean shells. Chitin presents itself as a promising target for the development of biopesticides. It focuses on unraveling the unique structures and biochemical pathways associated with chitin, aiming to identify vulnerabilities that can be strategically leveraged for effective and environmentally sustainable pest control. It involves a comprehensive analysis of chitinase enzymes, chitin biosynthesis, and chitin-related processes across diverse organisms. By elucidating the molecular intricacies involved in chitin metabolism, this review seeks to unveil potential points of intervention that can disrupt essential biological processes in target pests without harming non-target species. This holistic approach to understanding chitin-related pathways aims to inform the design and optimization of biopesticides with enhanced specificity and reduced ecological impact. The outcomes of this study hold great promise for advancing innovative and eco-friendly pest management strategies. By targeting chitin structures and pathways, biopesticides developed based on these findings may offer a sustainable and selective alternative to conventional chemical pesticides, contributing to the ongoing efforts towards more environmentally conscious and effective pest control solutions.

Preparation and Comprehensive Evaluation of the Efficacy and Safety of Chlorantraniliprole Nanosuspension

Chlorantraniliprole is a broad-spectrum insecticide that has been widely used to control pests in rice fields. Limited by its low solubility in both water and organic solvents, the development of highly efficient and environmentally friendly chlorantraniliprole formulations remains challenging. In this study, a low-cost and scalable wet media milling technique was successfully employed to prepare a chlorantraniliprole nanosuspension. The average particle size of the extremely stable nanosuspension was 56 nm. Compared to a commercial suspension concentrate (SC), the nanosuspension exhibited superior dispersibility, as well as superior foliar wetting and retention performances, which further enhanced its bioavailability against Cnaphalocrocis medinalis. The nanosuspension dosage could be reduced by about 40% while maintaining a comparable efficacy to that of the SC. In addition, the chlorantraniliprole nanosuspension showed lower residual properties, a lower toxicity to non-target zebrafish, and a smaller effect on rice quality, which is conducive to improving food safety and the ecological safety of pesticide formulations. In this work, a novel pesticide-reduction strategy is proposed, and theoretical and data-based support is provided for the efficient and safe application of nanopesticides.

Advances in understanding insect chitin biosynthesis

Chitin, a natural polymer of N-acetylglucosamine chains, is a principal component of the apical extracellular matrix in arthropods. Chitin microfibrils serve as structural components of natural biocomposites present in the extracellular matrix of a variety of invertebrates including sponges, molluscs, nematodes, fungi and arthropods. In this review, we summarize the frontier advances of insect chitin synthesis. More specifically, we focus on the chitin synthase (CHS), which catalyzes the key biosynthesis step. CHS is also known as an attractive insecticidal target in that this enzyme is absent in mammals, birds or plants. As no insect chitin synthase structure have been reported so far, we review recent studies on glycosyltransferase domain structures derived from fungi and oomycetes, which are conserved in CHS from all species containing chitin. Auxiliary proteins, which coordinate with CHS in chitin biosynthesis and assembly, are also discussed.

Validamycin Inhibits the Synthesis and Metabolism of Trehalose and Chitin in the Oriental Fruit Fly, Bactrocera dorsalis (Hendel)

The oriental fruit fly, Bactrocera dorsalis (Hendel), is a notorious invasive pest that has raised concerns worldwide. Validamycin has been demonstrated to be a very strong inhibitor against trehalase in a variety of organisms. However, whether validamycin can inhibit trehalase activity to suppress trehalose hydrolysis and affect any other relevant physiological pathways in B. dorsalis remains unknown. In this study, the effects of validamycin injection on the synthesis and metabolism of trehalose and chitin were evaluated. The results show that validamycin injection significantly affected trehalase activity and caused trehalose accumulation. In addition, the downstream pathways of trehalose hydrolysis, including the synthesis and metabolism of chitin, were also remarkably affected as the expressions of the key genes in these pathways were significantly regulated and the chitin contents were changed accordingly. Intriguingly, the upstream trehalose synthesis was also affected by validamycin injection due to the variations in the expression levels of key genes, especially BdTPPC1. Moreover, BdTPPC1 was predicted to have a binding affinity to validamycin, and the subsequent in vitro recombinant enzyme activity assay verified the inhibitory effect of validamycin on BdTPPC1 activity for the first time. These findings collectively indicate that validamycin can be considered as a promising potential insecticide for the management of B. dorsalis.